Setzer is the reigning champion of the Simulated Twilight Town Struggle tournament, where he fights with Roxas. In the real Twilight Town, he was the champion until Seifer defeated him in the last tournament.
Of all the Struggle opponents, Setzer is the easiest to defeat. Setzer's attacks are simple, although while using Roxas it is best to allow him to attack before counterattacking. He usually stands still on the arena until Roxas has hit him four or five times. Remember to pick up the orbs that are scattered around the arena after hitting him. When knocked back, Setzer will normally spin forward in the air attacking anything in sight.
When on low health and time, Setzer will power up his bat and rapidly stab the air. It is best to avoid him when he does this. Keep using hit-and-run tactics and he will fall.
When playing as Sora, use Trinity Limit to completely deplete his HP and remove most if not all his orbs. This can be done twice in a row by using the Reaction Command "Break". Simply run around and collect all of the orbs to end the battle.